That's because Gab is replete with far-right accounts that gained huge followings while pumping up Donald Trump’s message during the 2016 election, only to be later banned from Twitter for various types of disreputable behavior:

There’s “Ricky Vaughn,” an anonymous poster who once used an avatar of that character from the movie Major League, but now uses an image of a cartoon toad. There’s Jared Wyand, who got booted in late 2016 for ranting about Jews. And there’s “Microchip,” a juggernaut of a troll once referred to in a Buzzfeed article as a “Trumpbot overlord,” before getting kicked off of Twitter this year—either for spinning conspiracies about the October’s mass shooting in Las Vegas or for posting about “indoctrinating children into Nazi camps,” he told Newsweek. Another, more famous Twitter outcast, ex-Breitbart.com provocateur Milo Yiannopoulos, who was accused of using the platform to incite harassment against actress Leslie Jones, uses his Gab account only sporadically: as an emotionless vehicle for self-promotion.

Trump supporters are worried that they will fall victim to a so-called "Twitter purge," which they expect to start on December 18th, 2017. NICHOLAS KAMM/AFP/Getty Images

Gab is not Twitter. For one thing, there are only about 300,000 users, compared to Twitter’s more than 300 million, and only a fraction of them appear to be active. Nearly everyone on it seems to embrace some type of right wing ideology—meaning there are very few liberals around for trolls to target with hate speech. Trump isn’t on it, so his fans rely on an account that reposts what the president writes on Twitter as an alternative. Also, the trending topics don’t work the way they should: Long after the Alabama U.S. Senate special election had ended on Tuesday, for example, depressed Roy Moore supporters were stuck kicking the proverbial can down the road in a “Live Topics” section called “Upcoming Alabama Special Election.” Nevertheless, Gab is where some worried Trump supporters expect to wind up after Monday if the fabled “Twitter purge” plays out in reality.

We’ve updated our rules around abuse and hateful conduct as well as violence and physical harm. These changes will be enforced starting December 18. Read our updated rules here: https://t.co/NGVT3qGFvg

The origin for the “Twitter purge” idea is a mid-November post issued by @TwitterSafety, an official account hosted by the site that is focused on issues such as harassment and the incitement of violence. “We’ve updated our rules around abuse and hateful conduct as well as violence and physical harm,” the post said. “These changes will be enforced starting December 18.”

The part that is really spooking people, apparently, is an announcement from Twitter linked within the post suggesting that the company will be monitoring the behavior of users "on and off the platform"—leaving open the possibility that someone’s political affiliations could play a role in how they will be treated by the site going forward. Newsweek reached out to Twitter multiple times to request more details about what changes to expect from the platform after December 18, but has not received a response.

Since the announcement of the stricter rules, the notion of a “Twitter purge” has invoked paranoia in users on the far right, spanning neo-Nazis to religious conservatives to hardline Trump fans. For example, @apurposefulwife, an anonymous poster who runs a so-called tradlife blog that focuses on a hardline conservative approach to living for women (as in "traditional life"), despaired: “It doesn’t matter what I say. How many times I tweet that I don’t hate minorities, that I don’t believe in Nazism, the-powers-that-be have label me a Nazi and claim they know my inner thoughts,” read one post. For some broader context, the @apurposefulwife account doesn’t only focus on Christian values—the user frequently posts white nationalist memes, and communicates with white supremacist Richard Spencer.

Some explicitly neo-Nazi accounts—which are almost universally run by anonymous people—have been calling the December 18 the “great shoah’ing,” referring ironically to the Hebrew word for the Holocaust. Others are using a series of memes to count down the days until their accounts will be removed.

Scott Torok of Tucson, Arizona joined Gab in October and claimed to Newsweek that he had already been “purged” from Twitter based on ideology. He said he is a disabled war veteran who posted numerous “pro-military” tweets. “I exposed the left’s lies daily,” he boasted. Torok said he believes that Twitter is banning people like him based purely on ideology and that the trend will be exacerbated in the days ahead. To be clear, Torok's theory is not necessarily valid.

“I was purged,” he told Newsweek. “Twitter is definitely purging people. People are leaving because of censorship, harassment…101 reasons. ”

The reality of what Twitter is trying to do is more complex than people realize, observers say. For one thing, the site is responding to a deluge of criticism from users about hate speech: A multitude of accounts now put “ban the Nazis” in their names or bios, and there are active petitions to ban specific users, like conspiracy theorist Mike Cernovich. For another, the site has been inundated with bots. The company identifies “three million bot accounts per week,” according to Laura DeNardis, an internet governance scholar who is a professor in the School of Communication at American University in Washington.

DeNardis told Newsweek that companies like Twitter and Facebook are struggling to catch up in dealing with the breathtaking volume of complaints they now receive about things like foreign influence, bots, hate speech and targeted harassment. Also, there is a struggle to process what might be acceptable speech in one country but not another, given the speed at which the platform spreads language, ideas and images across borders.

The anonymous poster behind the “Ricky Vaughn” account, whose banning from Twitter before the 2016 election led to the trending hashtag #FreeRicky, told Newsweek that he felt the attempt to regulate content on Twitter has “a chilling effect on speech, and especially satire.” DeNardis acknowledged that the anonymous user, who frequently disparages women and Jews in posts on Gab, might have a legitimate point to make about censorship—particularly if Twitter really does start to analyze how people act while not on the platform, as opposed to dealing strictly with what they post online.

“I think it’s dangerous to free speech in general to make decisions about what happens outside of the platform,” DeNardis said in reference to potentially banning people based upon ideologies. “What we have to be careful about," she said, is to avoid having "the pendulum swing so far the other way” that free speech is curtailed during the attempt to ban hate speech and correct harassment issues.

Another potential threat to online free speech is this week’s Net Neutrality repeal decision, according to DeNardis and others who spoke to Newsweek about the issue. If Congress upholds the decision, “all bets are off” in terms of what can said online going forward, given the degree to which the loss of Net Neutrality would empower the private sector, she said. The issue is so murky that some rabid anti-Semites, including Andrew Anglin of the cartoonish neo-Nazi website Daily Stormer, have gone so far to argue that a repeal would somehow help him and others harass Jewish people. Multiple experts told Newsweek that this notion is flatly wrong, and that the move would empower companies like Twitter to be able to remove users.

Meanwhile, Gab has been marketing off the Twitter purge fears of many conservatives, even if it’s not clear how many people or who will be removed from the site.

“Twitter will be judging user behavior both on and OFF of their website,” claimed a recent press release. “This unprecedented level of censorship and blacklisting of groups from the public square is unlike anything in history and will be a huge opportunity for Gab.”